Docker credential helper for authenticating from environment variables

README.md

docker-credential-env

This is a very basic Docker credential helper that uses environment variables to authenticate to Docker. It's not as secure as the other credential helpers that Docker provides, but it can be very helpful in some circumstances (such as when using it with Jenkins).

To set this up, install the docker-credentials-env script somewhere in the Jenkins users path (it needs to be named docker-credential-env), then configure the Jenkins user's ~/.docker/config.json file to use it:

{ "credsStore": "env" }

To use it, you need to have the following environment variables set:

DOCKER_REGISTRY - Your registry URL
DOCKER_CREDS_USR - Your username
DOCKER_CREDS_PSW - Your password

If you are using Jenkins Declarative Pipeline, you can do this in the environment section of your Jenkinsfile (see the example Jenkinsfile).

config.json

{ "credsStore": "env" }

docker-credential-env

#!/bin/bash
# docker-credential-env
# 2018 - Jason Kohles

REG="${DOCKER_REGISTRY#https://}"
REG="${REG%%/*}"

die() {
  echo "$@" 1>&2
  exit 1
}

if [ -z "$REG" ]; then die "DOCKER_REGISTRY not set in environment"; fi
case "$1" in
  get)
    read HOST
    if [ "$HOST" = "$REG" ]; then
      printf '{"ServerURL":"%s","Username":"%q","Secret":"%q"}\n' \
        "$HOST" "$DOCKER_CREDS_USR" "$DOCKER_CREDS_PSW"
    else
      die "No credentials available for $HOST"
    fi  
    ;;  
  *)  
    die "Unsupported operation"
    ;;  
esac

Jenkinsfile

pipeline {
  environment {
    DOCKER_REGISTRY = 'https://my-docker-registry.example.com'
    DOCKER_CREDS = credentials( 'my-docker-credentials' )
  }
}

FYI, https://github.com/isometry/docker-credential-env seems to be a full-fledged repo dedicated to this concept.